Add histogram WebRTC.UserMediaRequest.Events to allow to track getUserMedia failures and hangs.

content/renderer/media/webrtc_uma_histograms.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_MEDIA_WEBRTC_UMA_HISTOGRAMS_H_
 #define CONTENT_RENDERER_MEDIA_WEBRTC_UMA_HISTOGRAMS_H_
 
 #include "base/memory/singleton.h"
 #include "base/threading/non_thread_safe.h"
 #include "content/common/content_export.h"
+#include "content/public/common/media_stream_request.h"
 
 namespace content {
 
+void LogUserMediaRequestResult(MediaStreamRequestResult result);
+
 // Helper enum used for histogramming calls to WebRTC APIs from JavaScript.
 enum JavaScriptAPIName {
   WEBKIT_GET_USER_MEDIA,
   WEBKIT_PEER_CONNECTION,
   WEBKIT_DEPRECATED_PEER_CONNECTION,
   WEBKIT_RTC_PEER_CONNECTION,
   WEBKIT_GET_MEDIA_DEVICES,
   INVALID_NAME
 };
 
@@ skipping 50 matching lines @@
 
   int num_streams_;
   bool has_used_api_[INVALID_NAME];
 
   DISALLOW_COPY_AND_ASSIGN(PerSessionWebRTCAPIMetrics);
 };
 
 } //  namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_WEBRTC_UMA_HISTOGRAMS_H_